In order of importance, for quick Zwift updates:
- Internet download speed (and just as importantly, ensuring ports aren’t blocked/restricted).
- Storage speed; mechanical hard drives are basically terrible.
- How up to date your system is with other Windows updates.
- Prevalence of unnecessary anti-virus software and other bloatware.
- CPU performance.
On a decent internet connection, with an SSD and a well maintained Windows 10 system, the monthly Zwift updates should take no more than a couple of minutes at absolute maximum. Most patches being under a minute. Anything more means there’s a bottleneck somewhere else in your setup.